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Basic support for FLAC-in-MP4 audio tracks #272

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Basic support for FLAC-in-MP4 audio tracks #272

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d17649e
Cache buffer.byteLength in NalByteStream.push
bvibber May 24, 2019
46e4327
Basic support for FLAC-in-MP4 audio tracks
bvibber Jun 1, 2019
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7 changes: 4 additions & 3 deletions lib/codecs/h264.js
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@ NalByteStream = function() {
swapBuffer.set(data.data, buffer.byteLength);
buffer = swapBuffer;
}
var len = buffer.byteLength;

// Rec. ITU-T H.264, Annex B
// scan for NAL unit boundaries
Expand All @@ -52,15 +53,15 @@ NalByteStream = function() {
// ^ sync point ^ i

// advance the sync point to a NAL start, if necessary
for (; syncPoint < buffer.byteLength - 3; syncPoint++) {
for (; syncPoint < len - 3; syncPoint++) {
if (buffer[syncPoint + 2] === 1) {
// the sync point is properly aligned
i = syncPoint + 5;
break;
}
}

while (i < buffer.byteLength) {
while (i < len) {
// look at the current byte to determine if we've hit the end of
// a NAL unit boundary
switch (buffer[i]) {
Expand All @@ -82,7 +83,7 @@ NalByteStream = function() {
// drop trailing zeroes
do {
i++;
} while (buffer[i] !== 1 && i < buffer.length);
} while (buffer[i] !== 1 && i < len);
syncPoint = i - 2;
i += 3;
break;
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2 changes: 1 addition & 1 deletion lib/mp4/audio-frame-utils.js
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Expand Up @@ -121,7 +121,7 @@ var generateSampleTable = function(frames) {
currentFrame = frames[i];
samples.push({
size: currentFrame.data.byteLength,
duration: 1024 // For AAC audio, all samples contain 1024 samples
duration: currentFrame.duration || 1024 // For AAC audio, all samples contain 1024 samples
});
}
return samples;
Expand Down
22 changes: 19 additions & 3 deletions lib/mp4/mp4-generator.js
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@

var UINT32_MAX = Math.pow(2, 32) - 1;

var box, dinf, esds, ftyp, mdat, mfhd, minf, moof, moov, mvex, mvhd,
var box, dfLa, dinf, esds, ftyp, mdat, mfhd, minf, moof, moov, mvex, mvhd,
trak, tkhd, mdia, mdhd, hdlr, sdtp, stbl, stsd, traf, trex,
trun, types, MAJOR_BRAND, MINOR_VERSION, AVC1_BRAND, VIDEO_HDLR,
AUDIO_HDLR, HDLR_TYPES, VMHD, SMHD, DREF, STCO, STSC, STSZ, STTS;
Expand All @@ -23,10 +23,12 @@ var box, dinf, esds, ftyp, mdat, mfhd, minf, moof, moov, mvex, mvhd,
avc1: [], // codingname
avcC: [],
btrt: [],
dfLa: [],
dinf: [],
dref: [],
esds: [],
ftyp: [],
fLaC: [],
hdlr: [],
mdat: [],
mdhd: [],
Expand Down Expand Up @@ -184,6 +186,13 @@ box = function(type) {
return result;
};

dfLa = function(track) {
return box(types.dfLa, new Uint8Array([
0x00, // version
0x00, 0x00, 0x00 // flags
]), track.metadata || []);
};

dinf = function() {
return box(types.dinf, box(types.dref, DREF));
};
Expand Down Expand Up @@ -465,7 +474,10 @@ stbl = function(track) {
};

audioSample = function(track) {
return box(types.mp4a, new Uint8Array([
var audioSampleBox = new Uint8Array([

// FLACSampleEntry extends AudioSampleEntry
// https://github.com/xiph/flac/blob/master/doc/isoflac.txt

// SampleEntry, ISO/IEC 14496-12
0x00, 0x00, 0x00,
Expand All @@ -488,7 +500,11 @@ stbl = function(track) {
0x00, 0x00 // samplerate, 16.16

// MP4AudioSampleEntry, ISO/IEC 14496-14
]), esds(track));
]);
if (track.codec === 'fLaC') {
return box(types.fLaC, audioSampleBox, dfLa(track));
}
return box(types.mp4a, audioSampleBox, esds(track));
};
}());

Expand Down